Imagers, usually laser imagers, are used to record electronically produced information on photographically sensitive media (e.g. photographic film or paper; or photoconductive drums, as in laser printers). Such devices are used in applications wherein information exists in an electronic form and a visually observable presentation of the information is desired. Typically a single beam of light is directed sequentially across a photosensitive media, in a raster scan fashion. Typically a laser (e.g. a gas laser beam) is used to create the beam.
Such imagers are used to create images when a computer is used to control or create the image information. Examples of the functions which are best done with computer assistance are: (1) size adjustment and cropping; (2) combinations of same or other photos into a layout; (3) addition of text or other graphics to photos; (4) color corrections (e.g. correction for use of daylight film with incandescent lighting); (5) unsharp masking (i.e. electronic sharpening of a photograph); (6) darkness and contrast adjustments; and (7) retouching. Hardcopy images are also needed when printing plates are being prepared, and a proof of the electronic image information must be obtained prior to preparation of printing plates from that same image information. Another example of needs for electronic imagers is in the preparation of medical x-rays (e.g. from CAT [Computerized Axial Tomography] or NMR [Nuclear Magnetic Resonance] scans).
One type of output recorder uses three lasers (one red, one green, and one blue) to create a latent image on photographic paper or film. Another type uses an accusto-optic modulator to modulate a noncoherent light source. Still another type uses light valves to modulate a noncoherent light source.
The light source is sometimes deflected by a moving mirror or set of mirrors (e.g. a polygon mirror) to obtain a raster scanning action on the photosensitive media. Another design directs the modulated light towards a rotating drum which has photosensitive media wrapped around it.
Once the latent images are created, the photographic paper or film is chemically processed to obtain a visually observable image.
Most such imagers require that one or more beams of light be modulated in order to create an image. It has been found, however, that some light modulators exhibit an undesirable sensitivity to temperature. Variations in temperature of a light modulator may create variations in response which, if not corrected, may create deviations in the image produced from the desired image. Therefore, a need exists in the art for a system for stabilizing the response of imaging systems, especially the light modulators therein, to variations in temperature, so that high quality, discontinuity-free images may be formed therewith.